In previously known foundry equipment of this kind, wear slats or wear plates are detachably secured to the structural parts of the equipment by means of threaded fasteners, e.g. screws countersunk in such a manner, that the top surface of their heads lie flush with the surface of the slats or plates. In the present specification and claims, the term "wear plate" is intended to include wear slats.
In order to make it possible to unscrew the threaded fasteners, the heads of the latter must necessarily be provided with some kind of screwdriver recess or the like. Even if the tops of the heads of the fasteners lie perfectly flush with the surface of the wear plate concerned, the screwdriver recesses will unavoidably constitute discontinuities in the surface. In the case of wear plates in moulding chambers, tiny protrusions on the sand moulds will be produced by the screwdriver recesses, and these protrusions will, when "scrubbed off" during the subsequent handling of the moulds, contaminate the moulds and/or the equipment with small quantities of sand which, although small are still capable of causing problems.
Further, if the countersunk screw heads do not lie perfectly flush with the surface of the wear plate concerned, relative movement between the wear plate and the sand moulds in contact with them may cause damage to the moulds, at the same time liberating small quantities of sand with the consequent problems.
A further disadvantage of using screwed fasteners is that they generally have to be screwed or unscrewed individually, thus requiring considerable time for attaching or detaching the wear plate concerned, also implying a risk of damage to the latter by inadvertent contact with the screwdriver bit.